FR3112994A1 - THERMAL SYSTEM VEHICLE WITH OPTIMIZED COOLING PERFORMANCE - Google Patents

Abstract

A vehicle (V) comprises a cooling circuit (CR) comprising a first heat exchanger (EC1) heating air by cooling a cooling fluid of an electric motor machine (MM), a heat pump (PC) comprising an evaporator (EV1), a compressor (CP) and a condenser (CD) in which a heat transfer fluid circulates, and a heating circuit (CC) comprising an air heater (AE) and a second heat exchanger (EC2) in which circulates a heat transfer fluid also circulating in the condenser (CD) and together treating air by exchange with this heat transfer fluid. The first (EC1) and second (EC2) heat exchangers are installed upstream of the first evaporator (EV1) one above the other so that air heated by this first heat exchanger (EC1) supplies the first evaporator (EV1) during a heating phase without supplying the second heat exchanger (EC2) during a cooling phase. Figure to be published with abstract: Fig. 1

Description

THERMAL SYSTEM VEHICLE WITH OPTIMIZED COOLING PERFORMANCE

Technical field of the invention

The invention relates to vehicles comprising an electric motor machine cooled by a cooling circuit and a reception area supplied with air treated by a heating circuit coupled to a heat pump.

State of the art

As known to those skilled in the art, certain vehicles, generally of the automotive type, comprise an all-electric or hybrid powertrain (or GMP), and therefore comprising at least one electric motor machine supplied with electrical energy by at least one battery rechargeable. The aforementioned vehicles are equipped with a cooling circuit comprising a first heat exchanger which cools, by exchange with outside air, a cooling fluid intended to reduce the temperature of their electric motor machine. This reduction is intended to reduce the consumption of electrical energy and therefore to increase the mileage range while reducing battery charging times (especially in regions where the climate is hot).

In this case, the vehicle is also generally equipped with a heat pump participating in the cooling/heating of the air which supplies its reception area (or passenger compartment) to improve the autonomy of the vehicle. This heat pump, which notably comprises an evaporator, a compressor and a condenser in which a first heat transfer fluid circulates, has the advantage of consuming a fairly low quantity of electrical energy and therefore reducing the range of the vehicle only slightly. This heat pump having an insufficient cooling (or refrigeration) capacity given its dimensions, it has been proposed to combine it with a heating circuit comprising a unit heater in which circulates a second heat transfer fluid also circulating in the condenser (from the heat pump) and suitable for treating air by exchange with this second heat transfer fluid to supply the reception area with treated air. It will be understood that the condenser is used to heat the heat transfer fluid of the heating circuit of the vehicle during a heating phase.

When the vehicle is used in the presence of high temperatures, typically above 35°C, the temperature of the second heat transfer fluid becomes significantly higher than the temperature of the outside air. This does not pose a problem with the heating circuit because the vehicle operates exclusively in cooling mode and therefore the unit heater does not supply the reception area with treated air. But this poses a problem at the level of the cooling circuit (during a cooling phase) because the condensation is not optimal at the level of the condenser because the first heat transfer fluid has a very high temperature (typically 100°C at the outlet of the compressor) and that the second heat transfer fluid has a temperature higher than that of the outside air (typically + 5°C to + 10°C) at the outlet of the unit heater. In other words, the cooling (or refrigeration) performance is insufficient to allow certain temperature setpoints chosen by certain passengers to be reached or only allows these temperature setpoints to be reached after long delays, which is detrimental to the perceived quality of the vehicle.

To avoid this degradation, we are forced to make the heat pump more complex, which turns out to be expensive.

The aim of the invention is therefore in particular to improve the situation.

Presentation of the invention

In particular, it offers for this purpose a vehicle comprising:

- a cooling circuit comprising a first heat exchanger heating air by cooling a cooling fluid of an electric drive machine,

- a heat pump comprising a first evaporator, a compressor and a condenser in which a first heat transfer fluid circulates, and together treating air by exchange with this first heat transfer fluid to supply a reception area with treated air, and

- a heating circuit comprising a unit heater in which circulates a second heat transfer fluid also circulating in the condenser and treating air by exchange with this second heat transfer fluid to supply the reception area with treated air.

This vehicle is characterized by the fact:

- that its heating circuit includes between the air heater and the condenser a second heat exchanger used during a cooling phase of the air to be treated in order to cool the second heat transfer fluid before it circulates in the condenser, and

- that the first and second heat exchangers are installed upstream of the first evaporator one above the other so that the air heated by this first heat exchanger supplies the first evaporator during a heating phase of the air to be treated without supplying the second heat exchanger during a cooling phase of the air to be treated.

Thanks to the invention, the first evaporator is now only used during a heating phase because it heats the first heat transfer fluid from the condenser by receiving air that has just been heated by the first heat exchanger.

The vehicle according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

- its heat pump may include a second evaporator inserted between the compressor and the first evaporator and used instead of the latter during each cooling phase of the air to be treated;

- its heating circuit may include a solenoid valve at the condenser outlet controlling either access to the second heat exchanger during each cooling phase of the air to be treated, or direct access to the unit heater during each heating phase of the air to be treated;

- its heating circuit may include between the unit heater and the condenser an electric heating device heating the second heat transfer fluid during a heating phase of the air to be treated;

- the second heat exchanger can be installed above the first evaporator;

- it can be of the automotive type.

Brief description of figures

Other characteristics and advantages of the invention will appear on examination of the detailed description below, and of the appended drawings, in which:

schematically and functionally illustrates a vehicle according to the invention comprising an embodiment of a thermal installation, with arrows materializing the directions of circulation of the various cooling fluids and heat carriers during a cooling phase of the air to be treated, and

schematically and functionally illustrates the vehicle of Figure 1, with arrows materializing the directions of circulation of the various cooling fluids and coolants during a heating phase of the air to be treated.

Detailed description of the invention

The aim of the invention is in particular to propose a vehicle V comprising an all-electric or hybrid powertrain (or GMP) and a thermal installation making it possible to optimize the maximum cooling (or refrigeration) performance of the air to be treated.

In what follows, it is considered, by way of non-limiting example, that the vehicle V is of the automobile type. For example, a car. But the invention is not limited to this type of vehicle. Indeed, the invention relates to any vehicle comprising an all-electric or hybrid powertrain and at least one passenger reception area (such as a passenger compartment, for example). Thus, the invention relates to all vehicles (land (except motorcycles), sea (or river), and air).

Furthermore, it is considered in what follows, by way of non-limiting example, that the GMP of the vehicle V is all-electric, and therefore comprises at least one electric motor machine MM. But the powertrain could be of the hybrid type, provided that it includes at least one electric driving machine and one driving machine of another type (for example thermal).

There is schematically and functionally illustrated in Figures 1 and 2 a vehicle V according to the invention, comprising a GMP (here represented by the single electric drive machine MM), a thermal installation CR, PC and CC, and a reception area EA (here a cockpit).

The electric driving machine MM is supplied with electrical energy by at least one rechargeable battery BR.

The thermal installation of a vehicle V according to the invention comprises at least one cooling circuit CR, a heat pump PC and a heating circuit CC.

The cooling circuit CR comprises a first heat exchanger EC1 responsible for heating air by cooling a cooling fluid of an electric drive machine MM. In other words, this first heat exchanger EC1 is responsible for cooling, by exchange with outside air, the cooling fluid which is intended to reduce the temperature of the electric motor machine MM.

For example, this cooling fluid can be water mixed with an additive, such as ethylene glycol or propylene glycol.

The heat pump PC notably comprises a first evaporator EV1, a compressor CP and a condenser CD in which a first heat transfer fluid circulates. The compressor CP is responsible for heating and pressurizing the cooling fluid which comes from the first evaporator EV1 (possibly after having passed through an accumulator AC) in a heating phase illustrated in figure 2, or else from a possible second evaporator ( internal) EV2 in a cooling phase (or refrigeration) to which we will return later. This compressor CP is preferably variable displacement.

The condenser CD is responsible for contributing to the heating or cooling of a second heat transfer fluid circulating in the heating circuit CC which passes through it. It will be understood that being of the fluid/fluid type, it allows an exchange of calories between the first and second heat transfer fluids.

For example, these first and second heat transfer fluids can be water mixed with an additive, such as for example ethylene glycol or propylene glycol.

This condenser CD is preferably sized so as to substantially completely condense the first heat transfer fluid from the compressor CP, in the heating mode, so that it is substantially completely in a liquid phase and partially cooled during the indirect exchange with the second heat transfer fluid. This allows an optimal transfer of calories.

The first evaporator EV1 is responsible, in a heating phase illustrated in FIG. 2, for heating the first heat transfer fluid which comes from the condenser CD (possibly via an expansion valve DT) by exchange with the outside air, that is to i.e. absorption of calories contained in the outside air. It then outputs a first heat transfer fluid, in the gaseous phase and slightly heated, which is intended to supply the compressor CP.

The possible DT regulator only intervenes in a heating phase illustrated in figure 2 and to which we will come back later. It is responsible for depressurizing the refrigerant which comes from the condenser CD, before it supplies the first evaporator EV1 in a heating phase. It delivers a first cooled and depressurized heat transfer fluid.

The heating circuit CC comprises at least one air heater AE and a second heat exchanger EC2 in which circulates the second heat transfer fluid which also circulates in the condenser CD. This unit heater AE and this second heat exchanger EC2 are suitable together for treating air (indoor and/or outdoor) by exchange with the second heat transfer fluid to supply the reception area EA with treated air. This heating circuit CC is therefore used to cool the first heat transfer fluid during a cooling (or refrigeration) phase illustrated in figure 1 and to heat the air to be treated during a heating phase illustrated in figure 2.

It will be understood that the objective of this second heat exchanger EC2 is to lower the temperature of the second heat transfer fluid as much as possible during a cooling phase so that the temperature difference between the first and second heat transfer fluids is as large as possible in the condenser CD to optimize the transfer of calories from the first heat transfer fluid to the second heat transfer fluid, and thus induce cooling by condensation of the first heat transfer fluid as much as possible. Certainly, when passing through the condenser CD the temperature of the second heat transfer fluid increases significantly, but it stabilizes quickly (typically at about 75°C when the temperature of the first heat transfer fluid is about 100°C and the temperature of the outside air is 45°C), which has no effect on the treated air which supplies the reception area EA since it only comes from the heat pump PC.

Here, the term “unit heater” means a heat exchanger of the air/fluid type.

The first EC1 and second EC2 heat exchangers are installed upstream of the first evaporator EV1 one above the other. Thus, the air which is heated by the first heat exchanger EC1 supplies the first evaporator EV1 during a heating phase of the air to be treated without supplying the second heat exchanger EC2 during a cooling phase of the air to be treated .

Thanks to the invention, the first evaporator EV1 is used only during a heating phase so that it can heat the first heat transfer fluid from the condenser CD, which is favored by the fact that it receives air which has been reheated at the first heat exchanger EC1. On the other hand, during a cooling phase, the first evaporator EV1 is not used because it would induce a degradation of the maximum cooling (or refrigeration) performance of its heat pump PC and therefore of the heating circuit CC due to the reception of d a heated air at the level of the first heat exchanger EC1. In fact, during a cooling phase, it is the second heat exchanger EC2 which is used because it is placed above or below the first heat exchanger EC1 and therefore receives air whose temperature is a priori lower. than that of the air heated at the level of the first heat exchanger EC1.

Note that in the example illustrated without limitation in Figures 1 and 2 the second heat exchanger EC2 is installed above the first evaporator EV1. But in an alternative embodiment not shown the second heat exchanger EC2 could be installed below the first evaporator EV1.

The heating circuit CC therefore operates in "short circuit" (without the second heat exchanger EC2) during a heating phase, and in "long circuit" (with the second heat exchanger EC2) during a cooling phase (or refrigeration ).

Preferably, the first heat exchangers EC1 and second EC2 and the first evaporator EV1 are installed in what those skilled in the art call the front facade of the vehicle V, where the outside air enters the frontmost part. (or upstream) of the engine compartment. It will be understood that an upstream part of the vehicle V receives air before a downstream part of the latter (V) when the vehicle V is moving forward.

It will also be noted, as illustrated without limitation in FIGS. 1 and 2, that the heat pump PC may comprise a second evaporator EV2 interposed between its compressor CP and its first evaporator EV1 and used instead of the latter (EV1) for at least minus each cooling phase of the air to be treated. To this end, the heat pump PC comprises a branch branch or "bypass" BD between the output of the condenser CD (or of the optional expander DT) and the input of the optional second evaporator EV2 in order to allow the first heat transfer fluid to go directly to the latter (EV2) without passing through the first evaporator EV1, and a solenoid valve V1 controlling the access of the first heat transfer fluid to this bypass branch BD or to the first evaporator EV1.

As illustrated without limitation in Figure 2, this second evaporator EV2 can also possibly be used during a heating phase of the air to be treated, in addition to the first evaporator EV1.

It will also be noted, as illustrated without limitation in FIGS. 1 and 2, that the heating circuit CC may comprise at the output of the condenser CD a solenoid valve V2 controlling either access to the second heat exchanger EC2 during each air cooling phase to be treated, or direct access to the air heater AE (without passing through the second heat exchanger EC2) during each heating phase of the air to be treated. In other words, the heating circuit CC comprises a first sub-part SP1 comprising the air heater AE and passing through the condenser CD, and a second sub-part SP2 comprising the second heat exchanger EC2. In a heating phase, the second heat transfer fluid is circulated only in the first sub-part SP1 (short circuit) in order to prevent the first evaporator EV1 from receiving outside air cooled by the second heat exchanger EC2. In a cooling phase, the second heat transfer fluid is circulated not only in the first sub-part SP1 but also in the second sub-part SP2 (long circuit) because the first evaporator EV1 is not used and therefore will not be influenced by the air from the second heat exchanger EC2.

It will also be noted, as illustrated without limitation in FIGS. 1 and 2, that the heating circuit CC may comprise between its air heater AE and the condenser CD an electric heating device DC heating the second heat transfer fluid during a heating phase of the air to be treated. It will be understood that this DC electric heating device is used as a back-up when the setpoint temperature of the treated air (supplying the reception area EA) is very high compared to the temperature of the outside air and /or when you need to condition the EA reception area very quickly.

For example, this DC electric heating device may comprise at least one heating resistor, possibly of the PTC ("Positive Temperature Coefficient") type.

It will also be noted, as illustrated without limitation in FIGS. 1 and 2, that the first sub-part SP1 of the heating circuit CC may comprise an electric pump PE, for example installed between the outlet of the condenser CD and the unit heater AE, and allowing to cause the second heat transfer fluid to circulate in the first SP1 and second SP2 sub-parts.

Claims (6)

Vehicle (V) comprising i) a cooling circuit (CR) comprising a first heat exchanger (EC1) heating air by cooling a cooling fluid of an electric drive machine (MM), ii) a heat pump (PC) comprising a first evaporator (EV1), a compressor (CP) and a condenser (CD) in which a first heat transfer fluid circulates and together treating air by exchange with this first heat transfer fluid to supply treated air to a space (EA), and iii) a heating circuit (CC) comprising an air heater (AE) in which circulates a second heat transfer fluid also circulating in said condenser (CD) and capable of treating air by exchange with this second heat transfer fluid for supplying treated air to said reception space (EA), characterized in that said heating circuit (CC) comprises between said unit heater (AE) and said condenser (CD) a second heat exchanger (EC2) used during a cooling phase ment of the air to be treated in order to cool said second heat transfer fluid before it circulates in said condenser (CD), and in that said first (EC1) and second (EC2) heat exchangers are installed upstream of said first evaporator (EV1) one above the other so that air heated by this first heat exchanger (EC1) supplies said first evaporator (EV1) during a heating phase of said air to be treated without supplying said second heat exchanger (EC2) during a cooling phase of said air to be treated. Vehicle according to claim 1, characterized in that said heat pump (PC) comprises a second evaporator (EV2) interposed between said compressor (CP) and said first evaporator (EV1) and used instead of the latter (EV1) during each cooling phase of the air to be treated. Vehicle according to claim 1 or 2, characterized in that said heating circuit (CC) comprises at the output of said condenser (CD) a solenoid valve (V2) controlling either access to said second heat exchanger (EC2) during each cooling phase of the air to be treated, or direct access to said unit heater (AE) during each heating phase of the air to be treated. Vehicle according to one of Claims 1 to 3, characterized in that the said heating circuit (CC) comprises between the said air heater (AE) and the said condenser (CD) an electric heating device (DC) reheating the said second heat transfer fluid for a heating phase of the air to be treated. Vehicle according to one of Claims 1 to 4, characterized in that the said second heat exchanger (EC2) is installed above the said first evaporator (EV1). Vehicle according to one of Claims 1 to 5, characterized in that it is of the automobile type.